Rotary pump



' Feb. 7, 1939. e. A. WAHLMARK ROTARY PUMP Filed April 1, 1955 3Sheets-Sheet l lllllllllll w ,W W 2 v. v Z a w fi 2 70 z d 1 w f K 5 2 4W 7. 7 w W Z w W 7 W x Feb. 7, 1939. G. A. WAHLMARK ROTARY PUMP FiledApril 1, 1955 3 Sheets-Sheet 2 s. WAHLMARK ROTARY PUMP Feb.

Filed April 1, 1935 3 Sheets-Sheet 3 I ,C. /M WWW w 4 W J f m. -fk pw/Patented Feb. 7, 1939 UNITED STATES 1o acter described which iscontrolled by pressure on the discharge side of the pump acting upon oneof the pump elements to vary the displacement of the pump automaticallyin accordance with the demand on the pump.

16 Another object of the invention is to provide a rotary pump having anautomatic air relief.

Another object is to provide a rotary variable displacement pump inwhich initial discharge does not take place until a predetermined pres-20 sure has been attained, which pressure is immediately increased tofull pressure at the com mencement of flow from the pump.

A further object of the invention is to perfect a pump having aninstantaneous cut-off of fiuid 26 discharge when the pump stops.

Yet another object of the invention is to perfect a pump in which thefinal discharge from the pump is at substantially the same pressure atwhich the pump has been discharging during 30 the remainder of theoperating period.

Yet another object is to provide a rotary, variable displacement pumphaving a single control means automatically varying the displacement,effecting initial and final discharge at full pres- 35 sure, andinstantaneous cut-off.

Yet a further object is to provide a rotary, variable displacementpumpconstructed to permit of convenient adjustment of the dischargepressure of the pump.

40 Yet a further object is to provide a two-stage, rotary pump havingbut a single shaft carrying two rollers each meshing with and drivingthe .rotor of one-of the stages.

Yet a further object of the invention is to provide a rotary pump havinga secondary stage operating automatically to displace varying amountsoffluid in accordance with the demand on the pump and a primary stage forcharging 50 the secondary stage, the driving elements of the stagesbeing mounted on a common shaft.

Other objects and advantages will become ap-' drawings, in which:

ROTARY PUMP Gunnar A. Wahlmark, Rockford, 111.

Application April 1, 1935, Serial No. 14,017

20 Claims. (Cl. 103-126) PATENT OFFlC Fig. 1 is a plan view of a rotarypump embodying the features of the invention.

Fig. 2 is an axial vertical sectional view taken along line 2-2 ofFigs.'1 and 4.

Fig. 3 is an end elevational view looking from the left in Fig. l. I

Fig. 4 is a sectional view taken along line 4-4 of Fig. 3.

Fig. 5 is a transverse vertical sectional view, taken along line 5-5 ofFig. 1. The figure is broken away in part. I

Fig. 6 is a fragmentary sectional view taken along the line 6-45 of Fig.3.

Fig. 7 is a transverse vertical sectional View taken along line 1-1 ofFig. 2. '15

Fig. 8 is an enlarged fragmentary view showing the construction of thesplines and recesses of the rotor and roller.

While the invention is susceptible of various modifications andalternative constructions, it is shown in the drawings and will bedescribed hereinafter as embodied in a preferred form of pumpparticularly well adapted for use with an oil burner. However, it is notintended that the invention is to be limited thereby to the specificform disclosed but it is intended to cover all modifications andalternative constructions falling within the spiritand scope of theinvention as defined by the appended claims.

As illustrated inthe drawings, the pump comprises a secondary stageoperating automatically to displace varying amounts of fluidinaccordance with the demand on the pump and a primary stage providedfor the purpose of charging the secondary stage when the pump isworkingv against an unusually high lift. Both stages are driven from acommon shaft and are enclosed in a common casing comprising generally acup-shaped housing ID, a cylindrical casing portion ll secured to theopen end of the housing l0, and a rotary mechanical seal, generallydesignated l2, closing the portion II. The housing I0 is formed withapertured ears l3 for securing the pump to a support and the cylindricalportion l l is secured to the housing In by bolts I4. A gasket I5 isinterposed between the abutting faces to make the joint fluid tight. Therotary seal is fully described and claimed in my copending applicationserial No. 704,705, filed December 30, 1933.

Considering now the details of construction of the pump, the variabledisplacement or secondary stage is housed in the housing III which, forthat purpose, is formed at its open end with a cylindrical bore I0slightly larger in diameter than '55 splines IS. The rotor is positionedconcentrically the bore ll of the casing portion II. The remainder ofthe housing constitutes an auxiliary reservoir as will appear later. Onepumping ele-'- ment of the secondary stage is formed by a rotor IS inthe form of a ring having a plurality of circumferentially spacedinwardly projecting within the cylindrical bore Ill but is of a diametersmaller than the bore so as not to be in direct contact therewith. Theother pumping element of the secondary stage is formed by a roller I!positioned eccentrically within the rotor 16 and having a plurality ofrecesses l'l meshing with the splines of the rotor with a rollingaction. The roller meshes with the rotor over a small portion only ofthe circumference thereof, herein the bottom portion, as best seen inFigs. 2 and 5. Herein the roller [1 constitutes the driving element ofthe secondary stage and to that end is secured by pin ill to a drivingshaft l9 extending outwardly through the portion II and the rotary seall2. The shaft I9 is journaled in a sleeve 20 one end of which abuts aface of the roller l1 and the outside diameter of which is equal to theoutside diameter of the roller to constitute one element of meansforming a chamber in which the pumping elements l6 and I! operate.

Also constituting a part of the means forming a chamber for the pumpingelements is an elongated tubular member 2! extending longitudinallywithin the casing. At one end this member has a cylindrical portion 22fitting in fluid tight relation within the bore. i I of the cylindricalcasing portion H and in turn bored eccentrically to receive a portion ofthe sleeve 20. The intermediate portion 23 is crescent shaped andpartially surrounds the remaining portion of the sleeve 20 and fills thespace between the eccentrically positioned roller and rotor. At itsremaining end, the member terminates in' a substantially cylindricalportion 24 disposed opposite the roller I! in abutting relation to aface thereof. Thus it is seen that the roller I1 is received between thecylindrical portion 24 and the sleeve 20 which, with the crescent shapedportion 23, completely enclose the roller except where it meshes withthe rotor IS. The outer circumference of the cylindrical-portion 24 isflush with the crescent shaped portion 23 joining therewith in a smoothuninterrupted surface. Both the portion 23 and the portion 24 arereduced from the cylindrical portion 22 to form an annular shoulder atthe joint between the housing I8 and the casing portion ll. shoulder onthe casing portion H resulting from the difference in diameter of thebores II and I0 form the end wall 25"of an annular chamber 25 the sidewalls of which are formed by the housing l0 and the sleeve 20 and member2|. The sleeve 20 and the member, 2| are prevented from rotating withthe shaft I9 by a pin 26 anchored in the casing portion H.

A single movable control means operates to complete the pump chamber, tovary, automatically the displacement of the pump, to effect initial andfinal discharge at full pressure, to effect instantaneous cut-off and tocontrol automatically air relief from the chamber 25. This meanscomprises a substantially annular piston 21 slidable longitudinally inthe bore l0 and encircling the crescent shaped portion 23 and the sleeve20, a collar 28 slidable on the cylindrical end portion 24 and acompressing spring 28 urging the collar 28 toward the piston and bothThis shoulder and I a toward the end wall 25'. At one end the piston 21is formed with an internal annular groove 38 in which the rotor I6 ispositioned, the rotor being retained in the groove and the groove closedby the collar 28 to complete a fluid tight but variable pump chamber forthe pump elements l6 andl'l. The collar 28 is secured against rotationwith the rotor I6 by means of a pin 3| engaging the piston 21. Pistonrings 21 may be employed to assure a fluid tight sliding fit between thepiston and the bore ll)".

To provide for the intake of fluid into the pump chamber and between thepumping ele-, ments, the cylindrical end portion 24 of the member 2| is.formed with an eccentric bore 32 communicating with the auxiliaryreservoir in the housing l0, and a radial passage 33 communicating withthe bore 32. The collar 28 is likewise formed with a passage 34constituting a radial extension of the passage 33, the combined passagesbeing disposed opposite the faces of the pumping elements at a pointrearwardly of the point of engagement thereof, that is, to the right ofthe point of engagement as shown in Fig. 5. The pumping elements l6 andI! operate in 2 well known manner to draw fluid through the bore 32 andpassages 33 and 34 into the recesses and the spaces between the splinesof the roller and rotor, the fluid being retained in the spaces by thecrescent shaped portion 23 until the rotor 3 and roller again meshwhereupon the fluid is forced out of the spaces. In addition to thecrescent shaped portion, the cylindrical portion 24, the sleeve 20, thepiston 21 and the collar 28 all aid in preventing escape of fluid fromthe 5 spaces between the teeth during rotation of the pumping elements.

As illustrated most clearly in Fig. 8, the rotor I 6 and the roller IIare of special construction designed to obtain unusually high volumetriceflig ciency and unusually high pressures while having a quiet andefficient operation. These advantages are obtained by designing therotor and the roller so that the latter engages the former in a rollingcontact which is substantially continuous and unbroken. Furthermore theroller engages the rotor in adriving and timing contact thus producing asecond seal. To that end the spaces l6" intermediate the splines 16' ofthe rotor and the tops of the splines are made,

concave and truly cylindrical, the center of curva-' ture of bothcoinciding with the axis of the rotor. The bottoms of the recesses andthe portions ll" of the roller are also truly cylindrical and convex,the center of curvature of both coin- I ciding with the axis of theroller. In addition the recesses in the roller l1 conform closely to thesplines on the rotor l6 and are adapted to receive the splines whollywithin so that when a spline meshes with a recess the top of'the splineand the bottom of the recess are in actual rolling. contact. Likewisethe portions l1" between the recesses of the roller contact and roll onthe portions |6"between the splines of the rotor.

To'obtain this rolling, substantially continuous 35 contact between therotor and the roller, the faces of the splines and recesses also aregiven a particular shape. Thus-the splines are slightly undercut at A ona very small radius. Immediately adjacent the undercut A the faces ofthe splines have a convex portion B with a radius of curvatureapproximately equal to one-half the width of the spline at thejuncture-between the convex portion and the undercut. The. remainder Cof the faces of the splines is also convex but -of the spline.

having a radius of curvature many times that of the portion B. Therecesses in the roller are formed so as to be complementary to thesplines of the rotor. That is, the outer corners of the recesses areformed with slight projections A of the same radius as the undercut A ofthe splines. Adjacent the projection A the face of the recess is formedwith a concave portion B having the same radius of curvature as theportion B The remaining portion C of the recess is also concave and hasthe same radius of curvature as the portion C of the spline. Thus itwill be seen that the entire spline is received within the recess sothat no fluid is trapped between the recess and the spline and so thatthe top of the spline is in contact with the bottom of the recess.

As shown herein the rotor is provided with eight splines while theroller has six recesses. With the diameter of rotor and roller hereemployed and with eight splines and six recesses respectively,successive splines and recesses are engaged before the preceding splineand'recess are disengaged so as to provide a driving connectionobviating the necessity of gearing for maintaining the rotor and rollerin timed relationship. As a result the rotor and roller here disclosedmay be considered as having two sealing contacts. The one is formed bythe rolling action of the roller upon the rotor which contact travelssubstantially uniformly along the circumference of the rotor as the sameis rotated. The second contact may be considered as that formed by thedriving engagement of the faces of the recess in the roller within thefaces of the splines on the rotor. The contact obtained between theperipheral portions of the roller and rotor is a purely rolling contactand may thus be very fluid tight without causing excessive wear andpower consumption. Because of this the pump is capable of producingunusually high pressures or vacuums. With the spacing and shape ofsplines and recesses here shown the rolling contact travelsprogressively along the peripheral portions and particularly over thetop of a spline to the edge of the driving face thereof before the facesof the spline and recess engage for a driving and sealing contact. Thusthere is no trapping of fluid in the bottom of the recess.

Discharge from the pump takes place through a channel 36 (see Figs. 4and 5) extending longitudinally of the pump and formed by cutting awayone tapering edge of the crescent shapedportion 23. The channel ispositioned with one and disposed opposite the faces of the pumpingelements just forwardly of the point of engagement thereof, consideredin the direction ofrotation, that is, to the left of the point ofengagement as seen in Fig. 5. At its other end the channel communicateswith the annular chamber 25. 'To complete the discharge passageway, achannel 31 is formed partly in the cylindrical portion 22 and partly inthe casing portion H (see Fig. 4). This channel. communicates at one endwith a channel 38 wholly in the portion II and registering with achannel 39 in the bearing 10. The channel 39 terminates in a recess orport threaded for the reception of a discharge pipe.

Means is provided herein for automatically varying the displacement ofthe secondary stage of the pump while maintaining a discharge of fluidat the same pressure and without changing the speed of rotation of thepump and without by-passing any of the fluid. Such automatic variationin the displacement of the secondarystage is under control of thepressure in the discharge passageway which operates through one of thepumping elements to increase or decrease the effectiveness of the stagedepending upon whether or not the pressure in the discharge passagewayfalls below or exceeds a predetermined value because the pump isdisplacing a quantity of fluid respectively less or greater than thedemand on the pump. This is accomplished by mounting the rotor It foraxial shifting movement relative to the roller l1 thereby to vary thearea of engagement between the two pumping elements of the secondarystage.

As previously stated the piston 21 and the collar 28, which form agroove in which the rotor I6 is retained, are axially slidable and withthe spring 29 form the means controlling the variation in displacementof the secondary stage of the pump. Normally the spring 29, acting incompression between the collar 28 and a disk 45 abutting an adjustingscrew 46 threaded in and projecting through the closed end of thehousing l0, retains the piston in its extreme forward position, that is,with the rotor and roller fully engaged. The spring 29 is calibrated inaccordance with the area of the face of the piston 21 so as to exert apredetermined force which is-overcome and permits rearward shifting ofthe piston and the rotor only after the pressure on the discharge sideof the pump and acting upon the piston reaches a predetermined value.Thus the rotor will always engage the roller to an extent such that thequantity of fluid displaced by the pump is equal to the demand on thepump within the capacity thereof. The pressure at which discharge takesplace is conven iently varied by adjusting the screw 46. Preferably theaperture through which the screw 46 projects is closed by a gasket 41and a screw plug 48 to render the casing fluid tight at that point.

In order that there may always be a space between the face of the piston21 and the end wall 25' so that the discharged fluid may at all timesexert a pressure on the face of the piston, a bushing 49 is disposed inthe channel 31 projecting a slight distance into the annular chamber toform an abutment. When the piston 21 is moved to obtain the maximumengagement between the pumping elements, it abuts the bushing 49 insteadof the end wall 25' and thus there is always an annular chamber betweenthe piston and the end wall into which the secondary stage discharges.Only one such bushing is employed so that the exposed area of the faceof the piston y when the piston abuts the bushing is reduced only by thearea of the bushing which is small compared with the total area of theface, thus assuring that the area of the piston exposed to pressure issubstantially constant throughout the entire operating period of thepump.

It will be apparent from the foregoing that the piston 21' inaddition-to varying the displacement of the pump also controls alldischarge therefrom. By abutting against the bushing 49 the pistoncloses the discharge passageway and retains the same closed until thepressure of the discharged fluid in the annular chamber is suificient toovercome the force of the spring 29 thereby assuring that discharge willtake place only at a desired predetermined pressure.

The axially shiftable mounting of the rotor l6 and piston 21, under thecontrol of the spring 29 and the pressure in the discharge passage,

results in another feature of applicant's construction, that is, a finaldischarge under full pressure as the pump is stopped. Thus, just as thepressure in the'discharge passageway is balanced against the strength ofthe spring 29 to vary the displacement of the pump in accordance withthe demand, so the spring operates to shift the piston forwardly, afterthe pump is stopped, at a rate suflicient to maintain full pressureinthe discharge passageway until substantially all of the fluid has beendischarged from the pump chamber 25.

It is also apparent that this axial shifting of the piston'2l by thespring 29 upon cessation of operation of the pump and the abutting ofthe piston against the bushing 49 operates to effect an instantaneouscut-off of the supply of fluid discharged from the pump. This cut-off issharp and precise and assures that final discharge will be atsubstantially full pressure.

I The axially shiftable means is employed herein for effecting yetanother feature, namely a bleedingor relief of air without the use ofthe usual relief valve, I To that end the piston 21 is formed with achannel 50 (see Fig. 4) terminating at its ends in restrictedsubstantially radial channels 50 and 50". The channel 50' communi cateswith the chamber through a groove 5| in the. portion 23 while the radialchannel registers with a channel 52 in the housing ill. The channel 52leads to a port 53 threaded to receivea pipe connected with a supplyreservoir not shown. The radial channels 50' and 50" register with thegroove 5| and the channel 52 in the housing only when the pumpingelements are in full mesh, that is, when the piston 21 abuts the bushing49 to close the discharge passageway. This air bleed is provided topermit the pumping elements to exhaust air from the casing and thesupply passages. During the period that air only is being pumped thepressure within the annular chamber 25 is not sufficient to move thepiston axially and thus-the air bleed passageway is maintained open.Immediately when the pump begins to discharge liquid, channels 50 and 50so restrict the flow of fluid that sufiicient pressure is built upwithin the annular chamber 25 to move the piston axially thereby movingthe channels 50" and 52 and channel 50 and groove 5| out of registry andclosing the air bleed passageway.

Communicating with the annular chamber 25 is a channel 55 (see Fig. 6)terminating in a u threaded recess 56 for the reception of a pressuregage (not shown) for indicating the pressure at which the pump isoperating.

The primary stage operates todisplace a constant volume offluidand isprovided for the purpose of lifting the fluid from the supply reservoirto the auxiliary reservoir in the housing l0 to maintain the secondarystage charged with fluid The primary stage comprises only a rotor 60 anda roller 6| meshing with and mounted eccentrically within the rotor.Here again the roller 6| is the driving element and to that endlssecured by means of a-pin 62 to the shaft- I 9 which thus .forms acommon shaft for the driving element of both the primary and thesecondary stage. Filling the space between the eccentricallymountedvroller and rotor is a crescent shaped'projection 63 formedintegral with. the tubular member 2|. The outer faces of the ele-- ments60 and BI are made fluid tight byan annular washer 64 secured inposition by the rotary mechanical seal 1 l2. Preferably the rotor 60 androller 6| are constructed in the same manner as the rotor and roller ofthe secondary stage.

Extending horizontally and longitudinally of the lower portion of thecasing is a duct 65 terminating at one end opposite the elements 60 and6| at a point just rearwardly of the point of engagement of the elementsto constitute a fluid supply passage for the primary stage. At the otherend the duct 65 ,communicates with a vertical duct 66 extendingdownwardlyinto com- 10 munication with a fuel bowl 61. This bowl issecured over a recess 68 formed in an appendage 69 of the pump casing.Fluid is supplied to the fuel bowl through an intake passage 10 formedin the appendage and terminating in a threaded 15 recess 1| for thereception of a supply pipe (not shown) extending to the main fluidreservoir. The fuel bowl 6'! is secured in position over the recess 68by means of a bale 12 provided with a screw and thumb nut 13 for forcingthe fuel bowl tightly against its seat. A gasket 14 is preferablyinterposed between the fuel bowl and the appendage to assure a fluidtight connection. Disposed within the bowl intermediate the sup.- plypassage ill and the vertical duct 66 is a double 1 screen 15 to preventforeign matter from reaching the pumping elements.

A second horizontally and longitudinally disposed duct 16 constitutesthe discharge passage for the primary stage and extends from a pointopposite the elements 60 and BI and just in adv vance of the point ofengagement of the-elements to the auxiliary reservoir formed by thehousing I 0 careof the excess amount of fluid supplied under thoseconditions the housing I0 is provided with a passage TI communicating atone end with the'auxiliary reservoir and at the other end with the airbleed outlet. Thus any excess fluid supplied by the primary stage isreturned to the main a reservoir through the air bleed outlet. It willbe seen from the foregoing that the primary stage serves merely tosupply the auxiliary reservoir {5 with fluid and does not constitute abooster for the secondary stage. It is also believediapparent that thesecondary stage functions entirely independently of the primarystage'and where the lift from the reservoir to the pump is not excessivethe secondary stage may be connected directly to the reservoir and theprimary stage omitted. The I primary stage pumps against no pressureexcept that offered by the restricted passage 11.

Briefly the operation of the pump is as follows:

Assume that the main supply reservoir has been freshly filled withliquid and that the pump is stopped. With the pump at rest the partswill by the secondary stage when the same is displac- 4 ing. less thanits maximum capacity. To take f be in the position shown in Fig. 4, thatis, the ele- I ments l6 and H of the secondary stage are-in 55 full meshand the piston 21 is in its forward. position abutting the sleeve 49 toclose the discharge passage and to complete or open the air bleedpassage. Now when the pump is started the primary stage will first drawair from the pipe 70 stage. Such pumping of air by the secondary stage,however, does not build up a pressure in the annular chamber 25 and thusthe piston 21 remains in its forward position closing the dischargepassageway and retaining the air bleed passageway open to permit theexhausting of air.-

When the air has been exhausted from the fuel bowl 61 and the passage 65the primary stage begins to pump liquid which likewise is discharged tothe auxiliary reservoir. The displacement of the primary stage isconstant and any excess liquid supplied to the auxiliary chamber isdischarged through the channel Such discharge of excess liquid alsoserves to carry with it air or vapor bubbles which may have formed inthe auxiliary chamber and thus assures a supply of liquid only for thesecondary stage.

Immediately upon commencement of a pumping of liquid by the secondarystage a pressure is built up in the annular chamber 25 sufficient tomove the piston 21 rearwardly against the action of the spring 29. Insuch movement the piston opens the discharge passageway and moves thechannels 50' and 50" out of register with the groove and channel 52 toprevent further discharge through the air bleed. The elements of thesecondary stage are so proportionedthat the maximum rated capacity ofthe pump is delivered when the piston is moved rearwardly a distancejust sufiicient to open the discharge passageway and close the air bleedpassageway. The extent to which the piston moves axially is such thatthe secondary stage displaces a quantity of liquid equal to the demandon the pump. Regardless of whether the demand varies or whether thedemand remains constant and the speed of the pump varies, the piston 21functions to maintain the rotor IS in such engagement with the roller IIthat the displacement of the pump is equal to the demand thereon withinthe capacity of the pump. Thus the pump may function as a variabledisplacement pump at either constant or variable speed 'or as a constantdisplacement pump at variable speed.

When the pump is stopped the piston 21 under the action of the spring 29moves forwardly at such rate that the predetermined pressure ismaintaineduntil the piston strikes and closes the bushing 49 in thedischarge passageway. Thus the final discharge is at the desiredpressure and the cut-off is instantaneous.

I claim as my invention:

1. In a rotarypump a casing having an inlet and an outlet passageway, arotor and a roller within said casing operable to discharge fluidforcibly therefrom, and an element within said casing responsive to thepressure on the discharge side of the pump controlling the outletpassageway from said pump casing and operating to vary the displacementof the rotor and roller.

2. In a rotary pump a casing having an inlet and an outlet passageway, arelatively shiftable rotor and roller within said casing cooperating todraw fluid into said casing and discharge the same therefrom, ashiftable control member carrying one of said pump elements and disposedto govern the outlet passageway, said control member being responsive tothe pressure on the discharge side of the pump and shifted thereby toopen the outlet passageway and determine the relative position of saidrotor and roller, and a spring urging said member to close the outletpassageway to retain the same closed until the pressure reaches apredetermined value.

3. A rotary pump comprising a casing having a bore, an outlet passagecommunicating with the bore and an inlet passage, means in part forminga pump chamber within the bore, rotary pump elements positioned withinthe chamber operable to draw fluid into the chamber from the inletpassage and discharge the same into the bore, one of said elements beingaxially shiftable relative to the other, and an axially shiftableelement completing the pump chamber and carrying the shiftable one ofsaid pump elements and governing by its axial shifting the outletpassage and the displacement of the pump in response to the pressure ofthe fluid within the bore.

4. A rotary pump comprising, a casing having a cylindrical bore, anoutlet passage at one end communicating with the bore and an inletpassage, means in part forming a pump chamber within the casing, pistonmeans slidable in the bore completing the pump chamber, a rotoropelating within the chamber supported by said piston means, for axialmovement, a roller eccentrically mounted within said rotor andcooperating therewith to draw fluid through the pump chamber, the pumpchamber communicating with the inlet passage and discharging into thebore in the casing, said piston means when in one extreme positionclosing oif the outlet passage and positioning the rotor in fullengagement with the roller, said piston means having an end face exposedto the fluid discharged from said chamber into the bore and urgedthereby toward the other extreme position -to open the outlet and shiftthe rotor away from full engagement with said roller, and a springopposing the action of the fluid on said piston and coacting therewithto govern the opening of the outlet and the displacement of the pump.

5. A rotary pump comprising, in combination, a casing having an inletand an outlet passage,

.means forming in part a pump chamber within said casing, rotary pumpelements within the chamber operable to draw fluid therethrough, thepump chamber communicating with the ,inlet passage in the casing anddischarging into the interior of the casing, and movable meansmaintained in contact with at least one of said pump elements forminganother part of the pump chamber and operating when the pump stops tochange the size of the chamber and thereby force out the fluid in thecasing under full pressure.

6. A rotary pump comprising, in combination, a casing having an inletpassage, a first outlet passage, a second outlet passage and conduitmeans communicating therewith, the first outlet passage being for thedischarge of liquid, the secont outlet constituting an air relief,rotary pump elements within said casing operable to draw fluid into thecasing and discharge it therefrom, one of said pump elements beingrelatively shiftable axially to vary the displacement of the pump bymodifying'the effectiveness thereof, and an 7 axially shiftable elementco-operating automateccentrically mounted within the rotor and housed insaid pump chamber, said rotor being carried by said piston and saidpiston being urged by the fluid pumped in a direction to unmesh saidrotor and roller, a shaft for driving said roller extending outwardlythrough one end of said casing, a mechanical rotary seal closing the endof the casing through which the shaft projects,

housed in said pump chamber with the roller eccentrically mounted withinthe rotor,roperating to draw fluid into the pump chamber and forciblydischarge the same into said annular chamber, and the rotor mounted insaid piston for axial movement relative to said roller, said casinghaving a discharge passage leading from said annular chamber, a shaftfor driving said roller extending past the annular chamber and outwardlythrough one end of said casing, a mechanical rotary seal closing the endof the casing through which the shaft projects, a compression springwithin the casing urging said piston in the direction of the projectingend of the shaft to effect a full meshing of said rotor and roller andto reduce the size of said annular chamber, and adjusting means for saidspring accessible from the exterior of the casing at the end oppositethe mechanical seal.

9. A rotary pump comprising, in combination, a cup-shaped housing havinga cylindrical bore at its open end, a cylindrical casing portion securedto the open end of said housing and having a bore therein, a tubularmember extending longitudinally of said casing having a firstcyllindrical end fitting within the bore of said casing portion, acrescent shaped intermediate portion reduced fromsaid end and a secondsubstantially cylindrical end joining with said crescent shaped portionin a smooth uninterrupted outer surface, said first cylindrical endhaving an eccentric bore therein, a sleeve extending through said bore,a-drive shaft journaled in said sleeve, a roller fast on said driveshaft and interposed between the opposed end faces 'of said sleeveandthe second cylindrical end, an annular piston slidable in the bore ofsaid housing and surrounding said crescent shaped portion and saidsleeve to form therewith an annular chamber, said piston having anannular internal groove, a rotor mounted in said groove and meshing withsaid roller over a portion of the circumference thereof, a collarslidable on the second cylindrical end and closing the groove in saidpiston to complete the pump chamber for said rotor and roller, a passageextending from the interior of said housing to a point rearwardly of thepoint of engagement of said rotor and roller to provide an intakepassageway therefor, achannel extending from a point in advance of thepoint of engagement of said rotor and roller to said annular chamber toprovide an outlet passage, a liquid discharge passage opening into saidannular chamber through the end wall thereofv and having a bushingprojecting inwardly to form an abutment against which said pistonstrikes, an air bleed passage formed in part in said piston and in partin said housing, the parts of said air bleed passage registering whenthe piston abuts the bushing of the liquid discharge passageway andbeing out of register immediately upon movement of said piston away fromsaid abutment, and a spring urging said collar adapted to cooperate withthe roller having a and annular piston toward engagement with thebushing in the discharge passageway.

10. A rotary pump comprising, in combination, a casing having alongitudinal bore therein closed at one end, a tubular member extendinglongitudinally of the bore and having a crescent shaped portion at oneend and a crescent shaped portion intermediate its ends, means includinga rotary mechanical seal forming with the tubular member and thecrescent shaped end portion thereof a fixed pump chamber, a rotor and aroller housed in said fixed pump chamber with the roller mountedeccentrically within the rotor and constituting a primary stage liftingfluid from a source and discharging the same within the casing at theclosed end thereof, means forming with said intermediate crescent shapedportion a variable pump chamber, a rotor and a roller housed in saidvariable pump chamber with the roller mounted eccentrically within therotor to constitute a secondary stage for discharging variablequantities of fluid from said casing, and a common shaft extending.outwardly through said mechanical rotary seal for driving the rollers ofsaid primary and secondary stages.

11. A rotary pump comprising, in combination, a casing having a bore, atubular member'having a first cylindrical portion fitting tightly withinthe bore, an intermediate crescent shaped portion, a second cylindricalportion at one end and a second crescent shaped portion at the otherend, said intermediate crescent shaped portion and said secondcylindrical portion being reduced from saidvfirst cylindricalportion'toform an annular chamber with the bore, the first cylindricalportion constituting the end wall of said chamber, said firstcylindrical portion having an eccentric bore therein, a sleeve extendingthrough said bore, a drive shaft journaled in said sleeve, a flrstroller fast on said shaft and-disposed between the second cylindricalportion and the opposed end of said sleeve, a second roller fast on saidshaft disposed opposite the remaining end of said sleeve, a washer and arotary mechanical seal closing the end of the casing through which saiddrive shaft projects and forming with the tubular member and the sleevea pump chamber, a rotor mounted within the chamber encircling the rollerand the crescent shaped portion to form a primary stage of the pump, anintake passage for said primary stage, a discharge passage leading tothe opposite end of said casing, means including an axially shiftablemember cooperating with said tubular member and said sleeve to completea second pump chamber, a rotor mounted foraxial movement with saidaxially shiftable member to form a secondaryv stage of the pump, anintake passage for said secondary stage and anoutlet passage leading tosaid annular cham-' ber, a discharge passage leading from said annularchamber having a bushing projecting into the chamber providing anabutment against which said axially shiftable member strikes, and aspring urging said axially shiftable member toward engagement with saidabutment to counteract the-pressure in said annular chamber and resistaxial shifting of the rotor until a predetermined pressure isestablished.

In a rotary p mp. a roller and a rotor the splines being cylindrical,with the center of 15 the radii of curvature coinciding with the axis ofthe rotor, said splines having slightly convex faces with a concaveundercut at the base of the splines forming thereby a reverse curve nearthe base, said roller having complementarily shaped splines and recessesadapted to engage the rotor during rotation in constantly progressivecon- .tact.

ture coinciding with the axis of the rotor, each face of said splinesbeing undercut on a small radius at the base of the splines, the portionimmediately adjacent the undercut portion being convex with a radius ofcurvature approximately equal to one-half the width of the spline, andthe remaining portion of the face being convex and with a substantiallylarger radius of curvature.

14. In a rotary pump, a rotor and a roller adapted to be mountedeccentrically within and mesh with the rotor, said roller having aplurality of circumferentially spaced recesses, the bottomsv of saidrecesses and the portions of the roller intermediate the recesses beingcylindrical with the radii of curvature coinciding with the axis of theroller, each face of said recesses terminating at its outer end in aconvex projection of a very small radius of curvature, the portionimmediately adjacent said projection being concave with a radius ofcurvature approximately equal to one-half of the width of said recess,and the remaining portion of each face being concave with a radius ofcurvature substantially larger than the adjacent portion.

15. In a rotary pump, a rotor rality of inwardly projectingcircumferentially spaced splines, the inner circumference of said rotorintermediate the splines and the ends of the splines being cylindricalwith the center of the radii of curvature coinciding with the axis ofthe rotor and a roller adapted to be mounted eccentrically within saidrotor having a plurality of circumferentially spaced recesses adapted tomesh with the splines of said rotor, the bottoms of said recesses andthe portions of said roller intermediate said recesses being cylindricalwith the radii of curvature coinciding with the axis of the roller toenable the roller to engage the rotor in a rolling contact, said splineshaving convex faces with a convex undercut at the base of the splinesand said recesses having concave facesand a convex -projection at theouter ends thereof, the concavity and convexity of the faces of therecesses being the same respectively as the convexity and concavity ofthe faces of the splines so that a spline may be received wholly withina recess without trapping fluid in the recess.

16. A rotary variable displacement pump comprising, a casing having a,cylindrical bore, an inlet passageand an outlet passage communicatingwith the bore, a rotor, a roller mounted eccentrically within said rotorand meshing therewith over a portion of itscircumference, a shaft fordriving said roller, stationary means including a portion of crescentshape interposed in thespace between the rotor and roller, extendinglongitudinally of the casing. in spaced relation thereto providing ajournal for said shaft and forming the part of a pump chamber in havinga plu- 1 which said roller operates, an annular piston having a slidingfit with said stationary means and the bore and having an annular groovefor supporting therein said rotor for axial movement relative to saidroller, the pump chamber so formed having an intake passage and apassage discharging into the bore, said annular piston when in oneextreme position positioning the rotor in full engagement with theroller and having an end face exposed to the fluid discharged from saidchamber into the bore and urged thereby toward the other extremeposition to shift the rotor axially away from full engagement with saidroller, and a spring opposing the action of the fluid on said pistonmeans and coacting therewith to govern the displacement of the pump.

17. In a rotary pump, a casing having a cylindrical bore forming in parta chamber, an inlet passage to the casing, and an outlet passage fromthe chamber, means extending longitudinally of the casing in spacedrelation to the walls thereof forming a pump chamber, an intake passagefor the pump chamber communicating with the casing and a dischargepassage leading to said chamber in the bore, rotary pump elements withinthe pump, chamber operable to discharge fluid to the chamber in thebore, an annular piston slidable in the bore and on the'pump chamberforming means and constituting oneend wall of the first mentionedchamber to be acted upon by the fluid in the chamber, said piston in oneextreme position closing off the outlet passage, but urged by the fluidin the chamber in a direction to open the outlet passage, and a springopposing the action of the fluid on said piston and coacting therewithto govern the opening of the outlet.

18. In a rotary pump a casing having a cylindrical bore, an inletpassage to the casing and an outlet passage leading fromthe bore, meansextending longitudinally of the casing in spaced relation theretoforming a pump chamber and partially defining a second chamber in thebore communicating with the outlet passage, said pump chambercommunicating with the inlet passage to the casing and discharging tothe second chamber, cooperating rotary pump elements within the pumpchamber, an annular piston axially slidable in said bore along said pumpsage being for the discharge of liquid, the secf ond outlet passageconstituting an air relief and both outlet passages communicating withthe bore in said casing, means extending longitudinally within thecasing in spaced relation thereto forming part of a pump chamber, aroller in that part of the pump chamber, an annular piston means axiallyslidable in the bore and along said means completing the pump chamber,said pump chamber communicating with the inlet passage and discharginginto the bore, a rotor supported by said piston means in cooperatingeccentric relation with and for axial movement relative to said roller,said piston means when in one extreme position closing off the firstoutlet passage, opening the air relief and positioning the rotor in fullengagement with the roller, said piston means having an end face exposedto the fluid discharged from the pump chamber into the bore and urgedupon the discharge of liquid toward an inlet passageway, a first outletpassage and a second outlet passage, means forming a pump chamber withinthe casing having an intake passage and a discharge passage adapted tocommunicate respectively with the inlet passage and the outlet passages,Dumping elements disposed in said pump chamber operable to draw fluidinto the chamber and forcibly discharge the same therefrom, a pistonslidable in the bore having an end face exposed to the fluid dischargedfrom said pump chamber and tended to beshifted axially thereby, a springresisting such movement of the piston by the pressure of the fluiddischarged, and a ductin said piston having one end in constantcommunication with the discharge passage from the said pump chamber, andthe other end adapted to register with said second discharge passagewhen the pump is discharging air only, and to be moved out of registerwith said second discharge passage when said pump is discharging liquidGUNNAR A. w HrMARK.

